# TEİAŞ Energizes 400/154 kV Autotransformer Expansions Across Marmara Transmission Ring to Safeguard Peak Industrial Load

> Türkiye’s state electricity transmission company TEİAŞ has successfully commissioned two new 250 MVA 400/154 kV autotransformers and modern GIS bays in the northwest Marmara grid ring, reinforcing supply to major industrial export corridors and stabilizing ENTSO-E synchronous interconnections.

- **Publish Date:** 2026-09-27
- **Category:** transformers-grid
- **Reading Time:** 5 min
- **Original Source Citation:** [TEİAŞ Transmission Control Directorate](https://www.teias.gov.tr/haberler/marmara-400kv-ring-sebekesi-trafo-kapasite-artislari-eylul-2026)
- **Tags:** TEİAŞ, Türkiye, 400 kV, Power Transformer, Substation, Marmara Ring, Grid Reliability
- **Canonical URL:** https://voltformer.com/news/teias-expands-400kv-marmara-ring-substation-transformers-autumn-peak
- **Markdown Source:** https://voltformer.com/news/teias-expands-400kv-marmara-ring-substation-transformers-autumn-peak.md

## Reinforcing High-Density Industrial Hubs Across Northwest Türkiye

The Marmara transmission ring, which accounts for more than one-third of the nation’s electricity consumption, experienced unprecedented autumn demand peaks driven by heavy manufacturing and expanded data center facilities around Istanbul, Kocaeli, and Tekirdağ.

The two newly energized 250 MVA autotransformer banks incorporate low-loss magnetic core designs, on-load tap changers (OLTC) with vacuum interrupters, and multi-gas online Dissolved Gas Analysis (DGA) systems to predict thermal degradation and insulation breakdown.

## Enhancing Cross-Border Synchronous Stability with Europe

The additional transformation capacity boosts transient stability along the Turkish grid’s interconnected tie-lines with Greece (IPTO) and Bulgaria (ESO), allowing higher scheduled commercial power exchanges.

Integrated ±100 MVAR STATCOM units and dynamic reactive power controllers deployed alongside the transformers maintain voltage stability during sudden transmission line trip events.

---
Related: [Power & Energy News Hub](https://voltformer.com/news.md) · [Voltformer Substation & Transformer Catalog](https://voltformer.com/catalog.md)